Brother International S-7200C Instruction Manual - English - Page 71

14. TROUBLESHOOTING Problem Possible cause 5 Skipped stitches at sewing y Is the thread take-up spring tension too strong? start Reduce the tension of the thread take-up spring. Thread unravelling at y Is the thread take-up spring operating range too large? sewing start Lower the position of the thread take-up spring. y Are the trailing lengths of the upper threads too short after thread trimming? Adjust the pretension. y Are the threads not being trimmed cleanly? Sharpen the fixed knives, or replace the fixed and movable knives if necessary. y Is the needle too thick? Try using a needle with a count that is one lower than the current needle. y Is the length of thread trailing out from the bobbin case after thread trimming too short? If the bobbin is spinning loosely, replace the anti-spin spring in the bobbin case. y Is the sewing speed too fast at the sewing start? Use the slow start feature. (G50 operation panel) Set so that slow start is enabled. (G10 operation panel) y Is the needle up stop position too high? 0749M Adjust the needle up stop position. 6 Uneven seam y Is the presser foot pressure too weak? Adjust the presser foot pressure. y Is the feed dog too low? Adjust the feed dog height. y Is the bobbin scratched? If the bobbin is damaged, smooth it with an oiled grindstone or replace it. 0473M 7 Large degree of puckering (excess tension) 0978M y Is the upper thread tension too strong? Make the upper thread tension as weak as possible. y Is the lower thread tension too strong? Make the lower thread tension as weak as possible. y Is the needle tip blunt? Replace the needle if it is blunt. y Is the needle too thick? Replace with as thin a needle as possible. y Are the thread take-up spring tensions too strong? Make the thread take-up spring tension as weak as possible. y Is the thread take-up spring operating range too large? Lower the position of the thread take-up spring to as low a position as possible. y Is the presser foot pressure too strong? Adjust the presser foot pressure. y Is the sewing speed too fast? Use the sewing speed control keys to gradually reduce the sewing speed. (G50 operation panel) Gradually reduce the maximum sewing speed (G10 operation panel) y Is the angle of the feed dog correct? Tilt the front of the feed dog down slightly. Page 56* 56* 44 * 15 27* 35* 28, 39* 44 58* 43 43 56* 56* 44 20 38* 59* S-7200C 64